Energy harvesting is the use of ambient energy to provide electricity for small and mobile equipment, whether electrical or electronic. Four main ambient energy sources are present in our environment: mechanical energy (vibrations, deformations), thermal energy (temperature gradients or variations), radiant energy (sun, infrared, RF) and chemical energy (chemistry, biochemistry).

In a recent report, titled "Energy Harvesting in Action -2012", market researcher IDTechEX noted that $700 million was spent on the energy harvesting component itself in 2011, rising to just under $5 billion in 2022.

The proliferation of mobile electronic devices has resulted in the development of new power sources. One alternative is human power, which has the advantages of being always available, requiring no chemical fuel or logistical measures.

Indeed, the human body is very flexible in generating applicable power from sources of heat dissipation, joint rotation, enforcement of body weight, vertical displacement of mass centers, as well as elastic deformation of tissues and other attachments. This opens up opportunities for harvesting energy to power mobile or implantable medical devices which could be used for a long time or be recharged permanently.

What follows are ten different human motion energy harvesting devices and technologies, in different stages of prototyping and application.

The amount of energy harvested thru these methods is ridiculously small except for the green wheel. You're better off putting a rechargable watch battery into devices along with wireless charging circuitry than use these methods. The exception being research into implantable pacemakers that never need removing.

Energy harvesting seems to be one of the next big thing in 2013. I wonder whether the energy is being harvested is actually needed elsewhere. Harvesting from breathing and body heat would probably has no side effect to the person. I would like to understand more about "Harvesting vibrations from heartbeats", etc.